Semaphore

[Rajath N R]

Hi,
    I think santosh is talking about user land IPC (semget). thread/process
which has acquired a sema lock/sem down using semop(2) syscall.



Thanks,
Rajath

On Fri, Feb 24, 2012 at 3:54 PM, Kristof Provost <kristof at sigsegv.be> wrote:

> On 2012-02-24 12:15:03 (+0200), Kosta Zertsekel <zertsekel at gmail.com>
> wrote:
> > I think of user land program opening a socket and crashing on
> > segmentation fault.
> > In code 'socket' syscall does:
> >     sock_map_fd --> sock_alloc_file --> alloc_file --> ... get lost ...
> > Where exactly in this case lock is held - I mean the lock that gets
> > released when user land process dies?
>
> In this case there doesn't appear to be any lock. The sock_map_fd
> function is most probably called from the socket syscall. This call
> isn't locked. Multiple processes can be in the socket syscall at the
> same time.
> There certainly won't be a (kernel) lock which is held between two system
> calls.
>
> Regards,
> Kristof
>
>
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-- 
Thanks & Regards,
Rajath N R
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